Final answer:
Graft-versus-host disease (GVHD) manifests after bone marrow transplants when donor immune cells attack the recipient's body, commonly causing rash, liver damage, and mucosal injury. It occurs due to the activation of the donor's cytotoxic T cells by APCs, and symptoms can vary from mild to severe, potentially affecting multiple organs.
Step-by-step explanation:
Graft-versus-Host Disease (GVHD)
Graft-versus-host disease (GVHD) is a complication that can occur after a bone marrow transplant, where the donated bone marrow contains immune cells that may attack the recipient's body. In GVHD, antigen-presenting cells (APCs) in the donated marrow recognize the recipient's cells as foreign, causing donor cytotoxic T cells to become activated and attack the recipient's tissues. This can lead to acute GVHD, characterized by a rash, liver damage, and mucosal injury. Symptoms are often variable, but the condition typically manifests with a skin rash, damage to the liver, and problems with the gastrointestinal tract such as the mucosa.
To mitigate the risk of GVHD, mature T cells are sometimes removed from donor bone marrow prior to transplantation. GVHD is a specific type of transplantation reaction, distinct because the transplanted immune system itself becomes the perpetrator against the recipient's tissue through activated T cells.
The symptoms of GVHD can include a rash at the entry site of the skin, fever, nausea, and difficulty breathing. In severe cases, GVHD can cause complications such as arthritis and damage to the kidney or heart.